2012 COURSE DATES: AUGUST 4 – 17, 2012 - Sirenian International

MANN: BEHAVIORAL SAMPLING METHODS 103
tacean behavior have received less attention. In this paper, I review quantitative
observational methods typically used in cetacean studies and offer specific sam-
pling suggestions.
Altmann (1974) points out that most field observations of behavior involve
sampling decisions, whether those decisions are explicit or not.
“Sampling decisions are made wbenever the stua’ent of social behavior cannot continuously
observe and record all of the behavior of all of the members of a social group. . , . We
suspect that the investigator ofen chooses a sampling procedure without being aware that
he is making a choice. Of course, he does not thereby escape fiom the consequences of that
choice.” (Altmann 1974:229).
The lack of an explicit protocol for sampling was termed ad libitum sam-
pling by Altmann (1974), and she pointed out that it typically entails scoring
“as much as one can” or whatever is most readily observable of the behavior
of a group (Altmann 1974:235-236). These kinds of observations may be
necessary as one learns to identify behaviors, as one plans a study, or as one
observes rare but significant events. However, ad libitum observations suffer
from a variety of potential biases. Different individuals may be more or less
visible. Some behaviors may be more salient and more readily recorded than
others. Individual animals may alter their behavior depending on how visible
they are to other animals (and to observers). The same observer may concen-
trate on different behaviors during different observation periods, and different
observers may notice or attend to entirely different behaviors during the same
observation period. Such biases indicate that ad libitum data are not appropriate
for estimating rates of behaviors or for comparing rates across subjects or across
studies. The selection and appropriate use of sampling methods that yield
unbiased estimates of behavior are critical to the scientific validity of any study.
In this paper, first I review the methods employed in the majority of recent
cetacean field studies, including sampling method and protocols, and discuss
the general advantages and pitfalls of each sampling method. Second, I rec-
ommend specific sampling methods for cetaceans, depending on identifiability
of animals, group sizes, dive durations, and change in group membership.
Literature Survey
To evaluate what methods are currently used by cetologists, I surveyed
papers on cetacean behavior published from 1989 through 1995 (see Appendix
1 for details). To limit the survey, I selected two peer-reviewed journals that
together published the majority of studies in wild cetacean behavior, The Ca-
nadian Journal of Zoology (CJZ, 31% of studies) and Marine Mammal Science
(MMS, 29% of studies).
Seventy-four studies were reviewed, 38 in CJZ and 36 in MMS. The fol-
lowing information was noted: species, age and sex classes, number of animals,
number of observation or recording hours, group-size minima and maxima,
whether animals were individually identified, types of behaviors recorded (in-
cluding vocalizations), definition of group and definition of behaviors, and